The National Institute on Drug Abuse (NIDA), Medications Development Division (MDD) has established a Cocaine Treatment Discovery Program (CTDP) to identify potential treatments for the medical management of cocaine dependence. This program involves testing compounds through a decision-based screening scheme which consists of a number of in vitro and in vivo assays and which is designed to identify potential treatment agents which either substitute for cocaine or antagonize the effects of cocaine. The purpose of this contract is to evaluate the effects of 20 test compounds on the reinforcing effects of cocaine, as assessed by the drug self-administration procedure. Specifically, the ability of the test compound to antagonize the reinforcing effects of cocaine will be determined by assessing the nature and magnitude of the shift in the cocaine dose-effect curve. The ability of the test compound to maintain self-administration behavior will be used to assess whether the test compound can substitute for the reinforcing effects of cocaine. Compounds will, in general, be submitted by NIDA to the contractor "blind" with a coded identification number and information about the compound such as their physical properties and solubility. CTDP data. generated from this contract on proprietary compounds will be maintained in confidence by NIDA for three (3) years from the date of reporting of the first test result to the compound submitter. After three (3) years, NIDA will disclose this information into the public domain through its MDD structure-activity database. Compound submitters are free to disclose CTDP data generated on their compounds prior to the three (3) year period of non-disclosure.